New Projects Could Transform Transatlantic ATM

Improving air traffic management over the Atlantic is a high priority for the aviation industry, and new initiatives are underway that promise a step change in efficiency and safety in this vital airspace.

A confluence of factors has sharpened the focus on routes between North America and Europe. This is the most important intercontinental traffic corridor, but while incremental ATM advances have been made, non-radar airspace rules have been a major constraint. Potential benefits are sizable, and new developments in procedures and technology mean some of that value can be realized.

Nav Canada and the U.K.'s NATS, which handle the bulk of transatlantic traffic, are continuing to refine their high-altitude highway network to improve flow. Air navigation service providers (ANSP) on both sides of the Atlantic, in conjunction with major aerospace companies such as Boeing, are testing increasingly advanced ways to optimize flight profiles. And gaps in radar coverage are being steadily closed, thanks to automatic dependent surveillance-broadcast (ADS-B) networks being established in Iceland and Greenland.

The transatlantic corridor is “one of the most economically important global routes, and it sustains a lot of commerce,” says Boeing Vice President for ATM Neil Planzer. “The biggest [potential] savings are over the North Atlantic. We know we do not operate as efficiently as we can, and we know we have the technology” to make improvements. Airlines “ply this route with some of the best-equipped aircraft in the world, and we do not take advantage of that.”

Nav Canada and NATS are putting a lot of effort into increasing the efficiency of the North Atlantic track system, which is adjusted daily and is used by about 1,200 flights a day. They work jointly on most initiatives so benefits extend all the way across the Atlantic. One such program reduces separation between aircraft on the same track and at the same altitude, and another being developed would reduce the distance between tracks.

The first of these is known as RLongSM, and allows longitudinal separation to be reduced to 5 min. from 10 for aircraft pairs that are properly equipped. It is used for about 200 aircraft pairs per month, even though it is technically still in trial mode. The appropriate regulatory groups have approved it, but the documentation is still in process, says Nav Canada's Vice President for Operations Larry Lachance. To participate, aircraft must have Future Air Navigation System (FANS) 1/A controller pilot data link communication (CPDLC) capability.

The other improvement being developed would reduce the lateral separation between the tracks, and is known as RLatSM. This will allow track separation of half a degree, or about 30 nm, versus the current standard of 1 deg. or 60 nm.

It would mean that within a 60-nm span, three tracks could be established instead of two, says Lachance. As a result, more tracks can be closer to the routes that are optimal because of wind and other conditions. “It will allow aircraft to benefit a lot more from the jet stream,” Lachance says.

If all goes according to plan, RLatSM could be introduced by Nav Canada and NATS in 2015. It would first be used on a trial basis at flight levels (FL) 350-390.

Efforts such as RLongSM and RLatSM allow pilot requests for more efficient altitudes to be granted more often. This means aircraft can adjust height according to wind conditions, and fly higher as their fuel load diminishes. Lachance says Nav Canada is working to educate pilots on its new capabilities. Many pilots have not been requesting altitude changes because they assume they will not be given clearance. “Now it's the other way around—we are asking them to make those requests, because they will often get approved.”

Nav Canada has implemented another feature it calls the request monitor tool, available to oceanic controllers through the Gander Automated Air Traffic System. If a pilot request for an altitude change is denied because of other traffic, the system stores the request and alerts the controller if that altitude change becomes available later. So the controller can go back to the pilot and offer the altitude change.

CPDLC is a precursor for many of these efforts. Nav Canada says equipage rates for FANS 1/A CPDLC is at about 65% over the North Atlantic. Nav Canada, NATS and the FAA all use it on oceanic routes. An International Civil Aviation Organization (ICAO) mandate entered force on Feb. 7, setting aside two of the core North Atlantic tracks—between FL 360-390 inclusive—where aircraft are required to use FANS 1/A equipment.

In addition to all these improvements, experts are looking further ahead—and more broadly—at how transatlantic traffic can be optimized.

By linking the U.S. and Europe, these routes connect two of the world's largest economies and air traffic systems, says Planzer. But inadequate coordination at either end means “we have, in effect, a non-system between these two big systems.” The two systems “only tangentially touch each other, and that causes problems.”

Planzer says coordination needs to occur among more players and cover the entire flight, beginning before takeoff, to make arrival times more predictable and to ensure smooth flows into congested airports at the other end of the trip.

To address this issue, Boeing is helping lead an “air bridge” project from the U.S. end that will link with a similar program underway in Europe. While the European effort has already been set up, the details of the U.S. initiative are still being ironed out.

At airports like London Heathrow, transatlantic flights often have to go into holding patterns before they land. Airlines are anxious for flights to take off as soon as possible to get better spots in the holding pattern when they arrive, Planzer says. Even where holding patterns are not used, “bunching” of transatlantic flights as they arrive in terminal airspace also leads to headaches for controllers at congested airports.

Under the air bridge concept, departure planning and en route speeds would be calculated to achieve a precise, predetermined arrival time that would in theory require no holding pattern or flightpath extensions, and improve the spacing of approaching aircraft.

“We want to work flow management back upstream far enough so simple speed adjustments can help [transatlantic flights] merge efficiently with other traffic,” says Chip Meserole, Boeing's director for advanced air traffic management. Currently, “there is not enough predictability for aircraft to do much beyond getting [airborne] and getting in line.”

Enhanced arrival management capabilities that the FAA and NATS are introducing will also help extend flow-control horizons farther over the ocean.

The intention of the air bridge is to essentially achieve a basic level of 4-D trajectories, Meserole says. These are flight profiles that include precise timing as the fourth dimension, and are integral parts of future ATM blueprints in many countries.

While it would be more complicated to adjust speed on the North Atlantic track system or under procedural air traffic control, there is much that can be done to adjust the timing of entry into these transatlantic flows, Meserole says. But even on the North Atlantic track systems, the new initiatives by the ANSPs are making it easier to allow speed and altitude changes.

A core concept needed for the air bridge initiative is information-sharing among the three or four air navigation service providers involved in most transatlantic flights.

The aim should be to improve efficiency on the routes linking the top five airports on either side of the Atlantic, Planzer says. “Air traffic management between these city pairs should be homogenized, rather than transiting four different systems.”

Transatlantic information sharing is already occurring to some extent. For example, the FAA has begun providing traffic data to Eurocontrol's Central Flow Management Unit, says Meserole. He notes that the real benefit comes from not just sharing information, but in its effective application.

A similar initiative to the air bridge has already been established on the European end. The Topflight program is being led by NATS, under a contract awarded by the Single European Sky ATM Research (Sesar) Joint Undertaking. Its first phase will involve up to 60 demonstration flights to and from London Heathrow over a four-month period. The aim is to optimize many aspects of transatlantic flights, including departures and arrivals.

NATS stresses that while one-off demonstration flights have been conducted under previous programs, this latest effort involves multiple flights—and in its second phase they will occur simultaneously. Boeing, Airbus, British Airways, Nav Canada and others are also involved in Topflight.

Boeing is pushing for the FAA to fund and launch a complementary program of demonstration flights focused on arrivals and departures from U.S. airports. The aim would be to develop concepts, prove they work and assess the benefits, with some elements left in place following the demonstrations.

Europe and the U.S. will have “separate but coordinated projects,” Planzer says. With the two sides concentrating on different aspects of the air bridge, “this will reduce the cost of each doing it independently.”

Planzer says the work could be assigned through the FAA's Systems Engineering 2020 program, and the team would probably be similar to that in the European effort.

However, securing a funding commitment in the U.S. has been the biggest obstacle so far. Meserole says the demonstration project would require “single-digit millions,” but the recent debate over mandatory cuts to the federal budget in the U.S. has complicated even relatively small funding requests.

The FAA is supportive of the air bridge initiative, but was initially targeting 2014 for full funding, Planzer says. However, he stresses the importance of moving in concert with the European project, and says he is confident at least some parts of the U.S. program can begin in 2013. More details on funding and timing are expected to emerge soon.

Meanwhile, separate transatlantic demonstration flight projects are continuing. Nav Canada is leading one such effort, known as Engage. This is primarily aimed at providing fuel savings and emissions reductions on oceanic flights, through the use of progressive altitude and speed changes.

Like Topflight, Engage is funded by a contract awarded through the Sesar Joint Undertaking. Air France-KLM and NATS are part of the Engage consortium. The first phase was completed last year, and the second will involve up to 100 flights with more airlines and ANSPs participating. By proving the safety case during the demonstrations, the Engage partners intend to “embed the procedure . . . for sustained application over the North Atlantic,” says Nav Canada's LaChance.

As well as improving procedures, expanding surveillance over the Atlantic has also been a major focus for Nav Canada and other ANSPs. The introduction of ADS-B has made this possible, since it has been impractical to build radar stations in remote locations that would help fill vast gaps in surveillance.

Nav Canada has ADS-B ground stations along its northeast coast that supplement its radar stations and provide offshore coverage. It has also sited ADS-B stations on the southern tip of Greenland that extend surveillance farther into the Atlantic.

The Greenland stations have yielded many benefits since they became operational in early 2012. Surveillance means aircraft are under direct air traffic control, allowing oceanic controllers based at Gander, Newfoundland, to further reduce separation and approve altitude changes even more readily. This has a domino effect on the North Atlantic routes, Lachance says. If westbound flights are able to achieve optimum altitudes, this in turn frees up more levels for following flights.

Nav Canada intends to add to its oceanic ADS-B surveillance by putting a ground station on the Hibernia off-shore oil platform, and an agreement with the platform's owners is expected soon.

Other ANSPs are also extending Atlantic ADS-B coverage. Iceland's Isavia and Denmark's Naviair are working on a connected series of ADS-B stations in the Faroe Islands, Iceland and Greenland that is intended to provide a surveillance corridor from European to North American airspace (AW&ST Oct. 22, 2012, p. 41).

This corridor will be farther north than routes for the bulk of the transatlantic traffic that Nav Canada and NATS are responsible for, but it will still cover some important traffic flows.

Isavia is responsible for installing the Iceland network—which largely overlays existing radar coverage—while Naviair is responsible for the Greenland and Faroe Islands sites. Isavia will provide high-altitude ATM services across all of these networks from its Reykjavik center.

This was originally intended to be a joint procurement project, but Naviair opted to pursue its own contract process for the Greenland ADS-B sites. Isavia selected Comsoft to provide its ADS-B stations, which have already been deployed and tested. They are expected to be used operationally this summer. Naviair, meanwhile, awarded a contract to Saab Sensis. Installation is expected this summer with surveillance data being transmitted by year-end. Limited operational use could begin in 2014, Isavia says.